I would certainly focus on the basic things you highlighted.
One more thing I have included in the terminal is the Risk Management configuration, which will display the Risk parameters for every trade initiated and position sizing would suggest, based on the capital available, how many qty...
I am building an online Trading Terminal and would like your views on what will you be looking for?
1. Advanced Charting - similar to TradingView - Trade From Charts
a. Typical Charts - available in Tradingview
b. Market Profile Charts
c. Orderflow Chart (footprint charts)